A recent development in video display systems is the use of spatial light modulators (SLMs) instead of raster-scan electronic beam devices. An SLM consists of an array of electronically addressable pixel elements. Each element emits or reflects light to be displayed on an image plane, such as a display screen. For many applications, an SLM is binary in the sense that each pixel element may have either of two states. The element may be off and deliver no light to the image planes or the element may be on and deliver light thereby forming an image.
One type of SLM suitable for use in display systems is the digital micro-mirror device (DMD), in which each pixel element is a tiny mirror capable of individual mechanical movement in response to an electrical input. Each pixel element of a DMD reflects and modulates incident light in direction, phase, or amplitude. Recent advances in the fabrication and use of SLMs, and DMDs in particular, permit a high pixel density for high quality video display systems.
SLMs are capable of addressing all pixel elements of each video frame simultaneously, rather than scanning them. Various techniques for exploiting this capability to provide high quality images are being developed.